allow negative data log plots with OpenGL+FLTK graphics (bug #34232) * mx-inlines.cc (mx_inline_any_positive): New function. * lo-mappers.h (xpositive_sign (double), xpositive_sign (float)): New functions. * fNDArray.h, fNDArray.cc (FloatNDArray::any_element_is_positive): New function. * fMatrix.h, fMatrix.cc (FloatMatrix::any_element_is_positive): New function. * dNDArray.h, dNDArray.cc (NDArray::any_element_is_positive): New function. * dMatrix.h, dMatrix.cc (Matrix::any_element_is_positive): New function. * graphics.h.in (log_scaler::do_neg_scale): New function. (log_scaler::scale (const Matrix&) const, log_scaler::scale (const NDArray&) const): Call do_neg_scale if no array elements are positive. * graphics.cc (axes::properties::get_axis_limits): Omit zero from positive values for log plots. Correctly widen range for all negative log plots.

--- a/liboctave/dNDArray.h
+++ b/liboctave/dNDArray.h
@@ -75,6 +75,7 @@
   boolNDArray operator ! (void) const;
 
   bool any_element_is_negative (bool = false) const;
+  bool any_element_is_positive (bool = false) const;
   bool any_element_is_nan (void) const;
   bool any_element_is_inf_or_nan (void) const;
   bool any_element_not_one_or_zero (void) const;